Motor vehicles – With means for promoting safety of vehicle – its occupant or... – Responsive to absence or inattention of operator – or...
Reexamination Certificate
1998-10-09
2001-02-13
Dickson, Paul N. (Department: 3618)
Motor vehicles
With means for promoting safety of vehicle, its occupant or...
Responsive to absence or inattention of operator, or...
Reexamination Certificate
active
06186260
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to arm rest and seat switches used as operational state sensors for work machines and, more particularly, to an arm rest/seat switch circuit configuration which enables an electronic controller to more accurately sense the proper parameters for enabling or disabling various machine systems and which yields a better logic combination for diagnostic purposes.
BACKGROUND ART
Arm rest and seat switches are commonly used as operational state sensors for work machines such as lawn tractors, skid steer loaders, integrated tool carriers, material handling machines, backhoe loaders and the like. As such, these switches are typically used to sense and detect when the machine operator is properly located in the machine prior to allowing movement thereof and/or enabling and/or disabling various systems associated with such machines. In the case of certain types of work machines such as a skid steer loader, from a safety standpoint, it is advantageous and necessary to ensure that the machine operator is, in fact, seated in the seat with the arm rest lowered to its operative or restraining position prior to starting the engine, and prior to engaging or activating the drive transmission, the implement lift and tilt mechanisms, and/or certain auxiliary hydraulic control systems and other functions. In these types of machines, such switches are commonly incorporated into an operator interlock control system whereby movement of the work machine and/or activation of some or all of the above-referenced systems are prevented unless certain operator safety parameters are met, namely, the operator is properly seated in the operator seat and the arm rest is down and in its restraining position. When so used, the operational state of the machine typically is detected by an arm rest/seat switch circuit configuration wherein the switches are coupled in a parallel arrangement to an electronic controller for sending input signals to such controller regarding the state or condition of such switches. A typical switch/sensor arrangement of this type is disclosed in U.S. Pat. No. 5,711,391 and is illustrated in FIG.
1
.
Based upon input signals received from the arm rest and seat switches, the electronic controller will analyze such inputs and thereafter provide appropriate output signals to accomplish various tasks. Since arm rest and seat switches have been wired in parallel to electronic controllers used in work machines, such circuit configuration results in a single line input for each respective switch to the electronic controller. This is clearly illustrated in
FIG. 1
wherein two independent switches
12
and
14
are coupled directly to an electronic controller
20
, switch
12
representing the arm rest switch and switch
14
representing the seat switch. In this parallel switch arrangement, arm rest switch
12
is connected to controller
20
via conductive path
16
and seat switch
14
is connected to controller
20
via conductive path
18
. In this particular circuit arrangement, latent faults in the circuit that result in normal operation will go undetected. For example, referring to
FIG. 1
, shorts to ground or open circuits on either the arm rest switch
12
or the seat switch
14
will go undetected as these failures look like a normal operating condition to controller
20
. More particularly, a short to ground on arm rest switch
12
will look to controller
20
as if switch
12
is closed thereby indicating that the arm rest is down and the machine is safe to operate regardless of the actual state or position of the arm rest. Similarly, an open circuit on switch
12
will look to controller
20
as if the arm rest is always up and the seat switch
14
failing in its closed position will appear to controller
20
as though the machine operator is properly positioned in the seat.
As a result, the prior art circuit configuration
10
does not always identify certain failures and when certain faults are diagnostically recognized, it is often times difficult to determine if a switch has failed or if a failure has occurred in the wiring harness such as conductive paths
16
and
18
. Additional troubleshooting of the system and circuit must therefore be accomplished in order to further isolate and detect the particular failure which has occurred, which additional action increases costs and machine downtime.
Improved diagnostic capability is therefore desirable. It is also desirable to build some redundancy into the arm rest/seat switch circuit configuration such that the input signals received from these switches are somehow tied together so as to give a better indication to the electronic controller that the operator is in fact properly located in the machine seat with the arm rest in its down and operative position.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In accordance with the teachings of the present invention, an arm rest/seat switch control circuit is disclosed wherein the arm rest and seat switches are wired or coupled in series such that the switch signals inputted to the electronic controller are tied together in a particular manner. Although different types of switches can be utilized with the present invention, the arm rest switch is preferably a proximity switch actuated by the lowering and raising of the arm rest and the seat switch is preferably a pressure actuated momentary switch that closes when the machine operator is seated in the seat. In the preferred embodiment, the arm rest switch is a noncontacting single pole, double throw reed switch which is actuated by a magnet. The magnet is preferably located on the arm rest and as the arm rest is moved between its up and down positions, the magnet comes in proximity to the switch and moves the switch from a first state or contact position to a second state or contact position.
During normal operation, when the arm rest is in its up position, the arm rest switch is normally closed against a first contact point thereby providing a first set of normally closed contacts and this state or condition is coupled or tied directly to the electronic controller such that the controller will sense both the normally closed and open positions of this first set of contacts. The second set of normally open contacts associated with the arm rest switch are wired in series to the seat switch which, in turn, is coupled or tied directly to the electronic controller. During normal operation, with the arm rest in its up position, the signal to the seat switch is open. On the other hand, when the arm rest is lowered into its operative down position and the operator is properly positioned within the seat, the arm rest signal from the first set of contacts to the electronic controller is open and the arm rest signal from the second set of contacts to the seat switch and then to the electronic controller is closed. As a result, the electronic controller will read both states of the arm rest switch and will continuously detect whether the arm rest is in its up position, but will only detect the arm rest in its down position when the operator is, in fact, positioned in the machine seat.
Because the electronic controller senses both states of the arm rest switch, the electronic controller will be better able to determine the proper operator parameters for machine and systems operation and the controller will be better able to perform diagnostics on the switches in order to detect and determine latent faults in the circuit configuration through the normal course of operation and thereafter take appropriate action. This circuit configuration therefore improves the programmable diagnostic capabilities of the controller and likewise improves the controller's ability to better determine the proper operator parameters for normal operating conditions.
It is also recognized that other types of arm rest/seat switches can likewise be utilized in the present invention to tie the arm rest and seat switch signals together
Schenck Raymond T.
Ufheil Steven T.
Blackwell Sanders Peper & Martin
Caterpillar S.A.R.L.
Dickson Paul N.
Fleming Faye M.
LandOfFree
Arm rest/seat switch circuit configuration for use as an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Arm rest/seat switch circuit configuration for use as an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Arm rest/seat switch circuit configuration for use as an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2566225